The present invention is directed to an x-ray device and method of fabrication, and more particularly to an x-ray device and method for fabrication for delivering localized radiation to vessels, lumens, or cavities of a body, such as cardiovascular tissue, to treat restenosis and other conditions.
In the medical field, doctors and scientists strive to find less invasive ways to treat patients. By using treatments that are less intrusive to the body, doctors can greatly reduce the stress on the patient""s systems and exposure to infection. For example, laparoscopic techniques enable physicians to explore the interior of the body and perform surgery through a small opening in the skin. Less intrusive medical techniques are extremely beneficial when applied to cardiovascular diseases.
Cardiovascular diseases affect millions of people, often causing heart attacks and death. One common aspect of many cardiovascular diseases is stenosis, or the thickening of the artery or vein, decreasing blood flow through the vessel. Angioplasty procedures have been developed to reopen clogged arteries without resorting to a bypass operation. However, in a large percentage of cases, arteries become occluded again after an angioplasty procedure. This recurrent thickening of the vessel is termed restenosis. Restenosis frequently requires a second angioplasty and eventual bypass surgery. Bypass surgery is very stressful on the patient, requiring the chest to be opened, and presents risks from infection, anesthesia, and heart failure.
Effective methods of preventing or treating restenosis could benefit millions of people. One approach uses drug therapy to prevent or minimize restenosis. For example, Heparin has been used as an anticoagulant and an inhibitor of arterial smooth muscle proliferation. Dexamethasone is another drug which may prevent smooth muscle proliferation. It has been suggested that such anticoagulants and antiproliferative agents may be effective at preventing restenosis after an angioplasty procedure thereby eliminating the necessity to repeat the procedure.
To be most effective and to reduce the associated risk, it is desirable to deliver such drugs directly to the region to be treated. In order to minimize the invasiveness of the procedure a drug delivery device that is adapted to traverse the human cardiovascular or circulatory system must be used. Such a device must be capable of entering small blood vessels with diameters of about two to four millimeters. Such a device must also be capable of making hairpin turns as it follows a tortuous path.
Many types of catheters have therefore been developed to deliver these and other effective drugs to the site of the restenosis. These catheters frequently use pressure to drive the drug into the tissue or plaque, potentially causing damage to the lumen wall. Techniques of delivery which do not use pressure use occlusion balloons to isolate the area from blood flow to enable sufficient absorption of the medication. However, the blood flow in an artery can only be occluded for a limited period of time while the drug is delivered. Due to these and other problems, localized delivery of drugs has not provided adequate treatment to prevent or reduce restenosis.
Another treatment for restenosis that has been attempted is beta-irradiation of the vessel wall by positioning radioactive isotopes in the vessel at the site of the restenosis. However, the depth of the penetration of the radiation is impossible to control with this method. The depth of the radiation is determined by the type of the radio-isotope used. The radioactive source will also irradiate other healthy parts of the body as it is brought to the site to be treated. Another disadvantage is that medical personnel must take extensive precautions when handling the radioactive material.
Thus, there is a need for effective methods and devices to treat the interior of the body with minimal intrusion. Effective, less invasive techniques for preventing and treating stenosis and restenosis at a lumen wall are especially needed.
Generally, the present invention provides a device to deliver localized x-ray radiation, and a method for fabricating such a device. In one particular embodiment of the invention, the device includes a cathode structure that has a thin, diamond film. The device further comprises an anode disposed within the vacuum housing, the diamond film being operative with the anode to produce localized x-ray radiation. In alternate embodiments, the device may further include a connector or a shaft, connected to the vacuum housing.
In another particular embodiment of the invention, a device to deliver localized x-ray radiation includes a cathode structure comprising a thin, diamond film on a getter. This device further comprises an anode disposed within a vacuum housing, the diamond film being operative with the anode to generate localized radiation.
In another particular embodiment of the invention, a method for fabricating a device for localized x-ray radiation is described which includes the formation of a thin diamond film on a shaped getter using a laser ion source. The method includes the steps of providing a getter with a shaped surface, where the getter has an activation temperature, and forming a thin diamond film cathode on the getter at temperatures below the activation temperature. The method further comprises disposing the cathode in a vacuum housing and increasing the temperature to the activation temperature of the getter.
In another particular embodiment of the invention, a transmissive device for insertion into the body of a patient is disclosed including a catheter and a flexible coaxial cable that is capable of conducting a voltage of greater than or equal to 10 kilovolts without electrical discharge.
In another particular embodiment of the invention, a method for conducting current in a body is disclosed, using the transmissive device of this invention.
In another particular embodiment of this invention, a device for insertion into a body includes a connector and a composite structure of boron nitride that joins a cathode and an anode.